Metal repair structure



DCC. 24, 1946. A G, DEAN y METAL REPAIR STRUCTURE original Filed Nov. 5, L1945 2 Sheets-Sheerl l FIGB F1616 INVENToR ALBERT G. DEAN a', ATTORNEY METAL REPAIR STRUCTURE Original Filed Nov. 5, 1945 2 Sheets-Shea?, 2

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z h\ XL J? \i@ 1; NVENTOR ALBERT G. DEAN BY Mada ATToRllEY Patented Dec. 24, 1946 METAL REPAIR STRUCTURE Albert G. Dean, Narberth, Pa., assgnor to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania @riginal application November 5, 1943, Serial No.

509,047. Divided and this application July 26, 1945, ASerial No. 607,143

8 Claims. (Cl. 189-34) This invention relates to sheet metal repair structures and has for an object the provision of improvements in this art. This application is a division of my copending application Serial No. 509,047, filed November 5, 1943.

It is now common practice to make aircraft coverings of sheet metal reinforced by frame members. The sheet metal covering is usually called the skin; the immediate frame members are called stringers; and the skin and stringers together may be designated as a skin blanket. Heavier frame structures support the skin blanket interiorly.

In service, particularly in combat, the skin blanket may be torn; and in most cases the dam- Fig 10 is a section taken on the line lillll aged areas are of relatively small extent, as Where of Fig. 7; projectiles have entered or emerged. However, Fig. 1l is a plan view of the skin repair sheets due to the fact that the total areas covered by alone; the skin blankets are usually very large, that Fig. 12 is a plan view of the closure frame most of the surfaces do not provide accommodaalone; tion for a mechanic and access to the interior; Fig. 13 is a plan view of the closure alone; and and that even when there is access to the in- Fig. 14 is a view similar to Fig. 6 showing the terior it is very diincult to cooperate with a repair structure for a larger damaged area. mechanic working on the outside, it becomes The damaged airfoil which is to be repaired desirable to provide a method and means for may, by Way of example, comprise a skin blanket making repairs to such damaged skin blankets l0 which includes a sheet metal skin Il and entirely from the outside. A subordinate factor stringere l2. It is assumed that the skin is torn which prevails in connection with riveted con-` as `indicated `by the jagged line i3 and the structions and to a greater degree in connection stringere are'broken or mutilated. For simplicity, with welded constructions is that it may be necitis represented that the stringers are .torn off essary to employ considerable pressure in making at the skin tear edge but it will be understood the joints and this can only be provided practhat this may not be the usual actual damaged tically by using a C-type yoke which has one arm condition. disposed inside the skin blanket and the other The rst step in making the repair is to cut outside. Provision must be made for the entry away the damaged structure to some regular of one arm through the skin blanket and means shaped opening represented by the line lli, as must be provided for closing the entry opening shown in Fig. 2. The .cut may be roughly made after the principal repair operations have been my a torch such as Oxy-acetylene or electric arc completed. The yoke arms are short, especially and the Vedges are trimmed back of the burned for emergency repairs, hence a method of repair material by metal trimmers of any convenient is needed which will be equally applicable to eX- type. tensive and limited areas of damage. As iar as At this stage, while there isa large access openpossible the repair, though made in emergency, lng all necessary repairs are made to the interior should be permanent in its nature. framework, such as `the ribs, spars, struts and The present invention is intended to provide the like, for making such repairs in a rapid and effective Next, string-er splicers I5 are provisionally semanner. cured as by tack welding to the ends of the cut The above and other objects and advantages stringere. If theY damaged area is small, the of the invention will be apparent from the fol- Stringer splicers may all be placed before any lowing description of an exemplary embodiment skin sections are applied, but if the area is large, thereof, reference being made to the accompanytherepair may be made in stages by adding suc` ing drawings, wherein: cessive stringers and widths of sheet skin ma- Fig. 1 is a plan View of a damaged airfoil which terial equal to the reach of the yoke arms of the is to be repaired; attaching tool which is used. Y

Fig. 2 is a similar View after the edges have 55 Upon the Stringer splicers I5 and overlapping been cut back to sound material;

Fig. 3 is a similar view after Stringer splicers have been placed;

Fig. 4 is a similar view after skin repair sheets have been secured;

Fig. 5 is a similar View after a closure frame has been secured;

Fig. 6 is a similar view after a closure plate has been secured;

Fig. 7 is an enlarged section taken on the line 'l--T of Fig. 6;

Fig. 8 is an enlarged section taken on the line 8-8 of Fig. 6;

Fig. 9 is an enlarged section taken on the line 9-9 of Fig. 6;

the edges of the skin around the opening there are placed one or more skin repair sheets I6 of any desired and convenient shape, as shown in Fig. 4. They, like the strngers, may rst be provisionally secured in position, as by tack welding, at a few points. Y

After the required stringer splicers and skin repair sheets have been placed and tack Welded for any sectional area within the reach of the arms of the pressure welding gun they are permanently welded by a pressure welding gun whose inner arm is inserted through the opening in the skin blanket.

Fig. 14 shows the application of additional stringer splicers and skin repair sheets I6. Two of the final stringer splicers are stub pieces, as in Fig. 3, to leave an opening for the welding gun between their ends.

After all the required stringer splicers and skin repair sheets have been permanently secured, there is left a final opening of a predetermined size, the edges of which aredesignated by the numeral I'I, as shown in Fig. 4. This opening is preferably bordered by the sides and ends of the stringer splicers I5. If not, it may be strengthened by any suitable doubler strips welded as a frame around the opening.

Among the repair supplies there is provided a standard closure frame I8 (Fig. 5) of predetermined size to t the nal opening which is left in the skin blanket. There may, of course, be a number of sizes of frames; but it is only necessary to show a selected one. This frame includes a plate portion I9 and an interior peripheral ange 20 extending inward therefrom and defining an opening whose edges are designated by the numeral 2I. The flange may be welded to the plate or made integral, as by stamping.

This smallest size opening is still large enough to pass the inner arm of the pressure welding gun, and the gun is now used to weld the frame to the repair skin and stringers. The frame may, of course, be first tack welded, if desired.

The edges of the frame plate and the underlying skin and stringers are drilled, preferably using preformed holes in a cover plate as a templet, and bolt or screw anchors of suitable type are secured at the inner ends of the holes.

Finally, a cover plate 22 is secured overthe opening by bolts or screws 23. The plate and frame may be provided with matching holes as originally made, for convenience. The frame then does not have to be drilled in making the repair but merely serves as a templet for drilling the skin and stringers.

The repair structure is designed to be as strong and rigid as the original structure without the cover plate; but the cover plate provides additional strength and, ifdesired, the plate may be provided with one or more stringers 24 welded thereto to give still greater strength.

It is thus seen that the invention provides an improved repair construction and an improved method of repairing a metal skin blanket. And although the repair is easily made as an emergency measure, the construction provided is as strongor stronger than the original construction and permanent in its nature. If cold rolled stainless steel was used, it may be matched in the repair structure with the same preservation of strength as in the original factory-made structure,

While one embodiment has been described by way of example, it is to be understood that the invention may have various embodiments within the limits of the prior art and the scope of the subjoined claims.

What is claimed is:

l. Repair structure for a skin blanket which includes a sheet metal skin and stringers, comprising in combination, Stringer splicers secured to the cut-off ends of damaged stringers at an opening leaving a small access opening without stringers, a repair skin secured to said stringere and the edges of the skin blanket at the opening leaving a small access opening where the Stringer splicers are omitted, a reinforcing frame secured to the edges of the repair skin around said access opening, and a closure secured to said frame.

2. Repair structure as set forth in claim 1, further characterized by the fact that said closureframe and closure are reinforced interiorly.

3. Repair structure for a skin blanket which includes a sheet metal skin and stringers, comprising in combination, stringer splicers welded to the cut-off ends of damaged stringers at an opening leaving a small access opening without stringere, a repair skin welded to said stringers and the edges or" the skin blanket at the opening leaving a small access opening where the stringer splicers are omitted, a reinforcing frame having a peripheral interior flange welded to the repair blanket at the small access opening, and a closure plate bolted to said frame.

4. Repair structure as set forth in claim 3, further characterized by the fact that said closure plate is reinforced interiorly by a stringer welded thereto.

5. Repair structure for a metal structure which includes interior frame elements and a covering skin, comprising in combination, frame element repair splicers secured to the cut-oi ends of damaged frame elements at the damaged opening, leaving a smaller access opening free of frame elements, a repair skin secured to the edges of the original skin and to the repair splicers leaving a small access opening where the repair splicers are omitted, a reinforcing border frame secured to the edges of the repair skin around said access opening, and a closure secured to said border frame.

6. Repair structure as set forth in claim 5, further characterized by the fact that said closure is reinforced interiorly by the frame elements.

7. Repair structure for a metal structure which includes interior frame elements and a covering skin, comprising in combination, one or more widths of repair skin at the opening caused by the damage between the edges of the original skin and a smaller opening where the repair skin is omitted to provide nal access, the repair skin being secured to the adjacent skin and to frame elements by attaching elements placed by opposed interior and exterior pressures, as by a .welding gun one arm of which will pass through the final access opening, a reinforcing border frame secured around the small final access opening, and a closure secured to said border frame.

8. Repair structure as set forth in claim 7, further characterized by the fact that said closure is reinforced interiorly by frame elements.

ALBERT G. DEAN. 

